
(f) SafeDrive
<FIGURE>
  
Refer to [1]}. Metadrive is a compositional, lightweight and realistic platform for vehicle autonomy. Most importantly, it provides pre-defined environments for safe policy learning in autopilots. Concretely, the observation is encoded by a vector containing ego-state, navigation information and surrounding information detected by the Lidar. We control the speed and steering of the car to hit virtual land markers for rewards (By default, [1]} conduct a reward shaping by penalizing collisions and overstepping the road; otherwise it would be too hard to learn), and the cost function is +1 if the vehicle collides with other obstacles or it is out of the road.

